UsefulTab
File Checksum Verifier
SHA-256 / MD5 for huge files, no upload.
Add a file to compute its checksum
Drop a file, pick SHA-256 or MD5, and compute its hash — then paste a publisher's checksum to verify integrity. Even a multi-gigabyte ISO is hashed in your browser and never uploaded.
Runs entirely in your browserVerify a file's checksum, locally
Drop any file — including a multi-gigabyte .iso or .dmg installer — and the verifier reads it in small chunks and streams them through a from-scratch SHA-256 or MD5 hasher, so only a tiny slice is ever in memory and the file is never uploaded. Paste the publisher's expected checksum and the tool tells you instantly whether it matches, so you know the download was not corrupted or tampered with. A progress bar tracks huge files, and the result is one click to copy.
Common questions
Can it handle a multi-gigabyte ISO without uploading it?
Yes. The file is read with the browser's Blob.slice API one chunk at a time and fed into an incremental hasher, so memory use stays small no matter how large the file is, and not a single byte leaves your device. There is no upload and no server involved.
Which algorithms are supported?
SHA-256 (the modern standard for integrity and the one most projects publish) and MD5 (still common for quick download checks, though cryptographically broken for security purposes). Pick whichever matches the checksum the publisher gave you.
How do I verify a download?
Drop the downloaded file, choose the algorithm the publisher used, and paste their published checksum into the compare box. A green match means the file is byte-for-byte what they released; a mismatch means it is corrupted, incomplete, or has been altered — do not trust it.
Why is MD5 offered if it is insecure?
MD5 is unsafe against a deliberate attacker, but it is still widely published for detecting accidental download corruption, and many legacy checksums are MD5. It is included for compatibility; prefer SHA-256 whenever the publisher offers it.
Is my file uploaded anywhere?
No. Hashing happens entirely in your browser using JavaScript. The file is read locally in chunks and never transmitted, so it works offline and keeps even sensitive files private.